This chapter is about what glaciers—and particularly what glacial and periglacial melt—mean to people and communities around the world. We often don’t realize that people interact daily with glaciers. Some go to visit and hike on glaciers or to photograph them for their magnificent beauty. Some ski on glaciers. Others extract water from glaciers for personal and industrial use. Others fear glaciers for their potent fury and destruction. People and communities are adapting to climate change and its impacts on glaciers, sometimes without even knowing it. Others are very aware of glacier vulnerability and are taking measures to address the changing cryosphere. They are mitigating circumstances and are adapting to impacts. In this chapter, we share stories and facts about glaciers and periglacial environments, which most people are probably unfamiliar with, and we explain how lives in these environments are changing due to climate change. Few people have heard of glacier tsunamis, but they exist, they’re real, they’re ferocious, and they can kill. Scientists call them glacier lake outburst floods (GLOFs). And as climate change deepens, more and more GLOF phenomena can be expected. Imagine you live at the foot of a mountain range like the Rocky Mountains, the Himalayas, or the Central Andes. On a nice sunny day, you can see the snow-capped mountains in the distance, maybe 20 or 30 km (12–18 mi) out, maybe even more. You are sitting at home when all of a sudden you feel shaking and hear a rumble. People start screaming. You look out the window and see people running frantically and erratically about. Then a woman yells, “The mountain! It’s coming! Run!” Imagine a large glacier the size of a dozen or so city blocks, perched atop a mountain. It’s 180 meters thick (600 ft), which is as tall as a sixty-story building. Below it, time and climate have formed a lake, a glacier lake occupying the same spot where the glacier once rested, pushing rock and earth out and forward as the glacier flowed downhill when it was solidly frozen and healthy.
